Home» Graphene Fexible Electronics
Recent advances in ultrathin electronic devices have broadened the scope of flexible/stretchable electronics from flexible circuits, foldable displays and flexible energy harvesting/storage devices to the advanced stretchable and wearable biomedical devices that can integrate with the complex curved geometries to closely monitor and record the various vital bio-signals.
The poor mechanical properties of conventional inorganic electronic materials greatly hinder their integration in flexible/stretchable applications, which motivated researchers to make efforts in developing alternative materials, with excellent mechanical endurance against bending/stretching, that can be coupled with shape-conforming systems maintaining the functional properties and electronic performance parameters unaffected with body movements.
Researchers have suggested graphene applications in the related fields of printed and flexible electronics. The dream has been highly functional, mechanically flexible devices fabricated by large area and high speed printing processes, and applied to a wide array of substrates with a broad range of form factors (conformal, curved, light weight). All of this would enable novel devices with better durability, high-levels of functional integration and produced using mass production processes with high yields and low costs.
In the efforts to investigate materials for developing efficient flexible/wearable devices, graphene has emerged as a most promising material in the last decade. Its excellent mechanical properties with huge tensile strength ~130 GPa, Young’s modulus of ~0.5–1 TPa, spring constant ~1–5 N/m, and stretching ability (elasticity) make it highly suitable material for flexible and stretchable/wearable devices. In addition, the other outstanding material properties of graphene, such as high chemical and thermal stability, large specific 2-D surface area for conformal adhesion of the other materials/substrates, wide optical absorption spectrum (300–1400 nm), excellent transparency of ~97% in the visible wavelength range, piezo and thermo-resistive response, and electrical sensitivity towards biochemical’s, make it a most promising multifunctional material for flexible devices. However, the electronic properties of graphene have been realized as unique features till now over other available electronic materials such as its ultra-high electronic mobility (15000–200000 cm2 / (V·s)) due to the ballistic transport of carriers, ambipolar behavior, and high conductivity comparable to conventionally available indium tin oxide.
Graphene with an exceptional combination of electronic, optical and outstanding mechanical features has been proved to lead a completely different kind of 2-D electronics. The most exciting feature of graphene is its ultra-thin thickness that can be conformably contacted to any kind of rough surface without losing much of its transparency and conductivity. Graphene has been explored demonstrating various prototype flexible electronic applications, however, its potentiality has been proven wherever transparent conductive electrodes (TCEs) are needed in a flexible, stretchable format.
There are however, potential printed and flexible electronic applications that build upon the unique properties of graphene. Graphene added to polymer films can create flexible materials with an array of desirable functional properties. Plastic layers and devices can be created with simultaneously high electromagnetic shielding, high oxygen barrier and strong anti-abrasion properties, for example. Thin layers of novel graphene-enhanced polymers can provide enhanced thermal and electrical conductivity, or perhaps just one or the other depending on the fabrication process. Innovative techniques can provide gradients or patterning of electrical conductivity in graphene polymer nanocomposites. All of these examples would be based upon polymer composites, offering mechanical flexibility and the possibility of high volume, low cost fabrication processes.